The bed device is able to realize various kinds of operations such as back rise and knee rise in bed mode by operating the actuators connected to the bottom part so as to change mode into a condition suitable for the patient and change the shape of the bottom part in conformity with the patient's posture.
Herein, for the bed device, there is a known function, which, in advance, prohibits risky control against the patient (bed control prohibiting function or the like). In use of the bed control prohibiting function, when a predetermined control has been prohibited in advance, if the person (operator) who operates the bed device performs the predetermined control it is possible to avoid, for example a dangerous operation that would cause the patient to fall from the bed.
There has been another known invention, by which the position of the patient on the bed device is detected so as to give an alarm when the patient stays in a dangerous position (e.g., see Patent Document 1). This configuration makes it possible to notify the operator when the patient is staying at a hazardous position where the patient would fall from the bed device or be strongly caught into the bed.